boost::signals build and C++Builder 6 Pro in 1.29.0

From: Russell Hind (yg-boost-users_at_[hidden])
Date: 2003-03-03 05:57:25

I have built the boost::signals library with C++Builder 6 Pro Update 4 
and am running into problems:

a) We tend to use double word alignment, not quad word (which is the 
default in C++Builder).  It appears that the libraries are built with 
quad word, but the headers don't enforce this, so when I change the 
options to double word (in our project) and try to construct a signal with

boost::signal0<void> s;

I get an access violation when constructing a signal (from line 266 of 
shared_count.hpp)  The call stack is

00417F3F __internal_malloc
00417DD8 __internal_malloc
00417539 ___org_malloc
00416EA2 ___org_new
004076E1 boost::detail::shared_count::shared_count(this=:0012FBB4, 
p=:007F3928, d={  },  =:007F3928)
004063E3 
boost::shared_ptr<boost::signals::detail::signal_base_impl>::shared_ptr<boost::signals::detail::signal_base_impl>(this=:0012FBB0, 
p=:007F3928)
0040546D 
boost::shared_ptr<boost::signals::detail::signal_base_impl>::reset<boost::signals::detail::signal_base_impl>(this=:0012FF70, 
p=:007F3928)
00403F51 
boost::signals::detail::signal_base::signal_base(this=:0012FF70, 
comp=:0012FC24)
0040232E boost::signal0<void, boost::last_value<void>, int, 
_STL::less<int>, boost::function0<void, boost::empty_function_policy, 
boost::empty_function_mixin, _STL::allocator<boost::function_base> > 
 >::signal0<void, boost::last_value<void>, int, _STL::less<int>, 
boost::function0<void, boost::empty_function_policy, 
boost::empty_function_mixin, _STL::allocator<boost::function_base> > 
 >(this=:0012FF70, c=:0012FC7C, comp=:0012FC74)
00401BF3 main(argc=1, argv=:007F21E4)
00420862 __startup

b)  If I do use quad word alignment, then the object constructs 
correctly, but when I connect a method to it with

void VoidFunc(void)
{
}

int main(int argc, char* argv[])
{
boost::signal0<void> s;
     s.connect(&VoidFunc);
}

the program hangs.  Turning on CodeGuard shows a similar problem to that 
above.  The object was allocated with a size of 12 bytes, but code is 
trying to access byte 16 in the object (I guess this is a similar 
alignment problem).  The callstack is

0041E44E boost::counted_base::dispose(this=:00C04360)
00427203 boost::signals::detail::signal_base_impl::connect_slot
00404741 boost::signal0<void, boost::last_value<void>, int, 
_STL::less<int>, boost::function0<void, boost::empty_function_policy, 
boost::empty_function_mixin, _STL::allocator<boost::function_base> > 
 >::connect(this=:0012FF60, in_slot=:0012FDA8)
004026C5 main(argc=1, argv=:00C021E4)
00433802 __startup

It says the this pointer block is only 12 bytes long, but the code is 
trying to access byte 16.

Do (or should) all the bost headers force alignment before all 
structures/classes and then restore the alignment afterwards?

Currently, I have to link directly with the signals source code to get 
use the library.

Has anything to do with this been changed in the builds of 1.30.0?

Thanks

Russell